Mounting assembly of integrated circuit device and method for production thereof

ABSTRACT

A mounting assembly of an integrated circuit device includes an integrated circuit device having pads on its lower side, through holes formed in a mounting substrate at positions opposed to the pads of the integrated circuit device, and solders for connecting the pads of the integrated circuit device with the through holes. An electrode is provided on the inside wall of each through hole, and the mounting substrate includes therein wirings connected to the electrodes. The solder is filled into the through holes to such an extent that the solder filled in the through holes can be visually checked from the lower side of the substrate.

This is a division of application Ser. No. 09/032,844 filed Mar. 2,1998, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to mounting assemblies of integratedcircuit devices and methods for production thereof and moreparticularly, to a mounting assembly of an integrated circuit device inwhich an interconnection between an integrated circuit device and amounting substrate is not exposed and also to a method for productionthereof.

2. Description of the Related Art

An example of this type of prior art mounting assemblies of integratedcircuit devices is disclosed in PCT International Publication Number6-504408/94.

In FIG. 13 of the above Publication, a semiconductor chip assemblyincludes an integrated circuit device having a plurality of input/outputterminals provided on the periphery of its top surface and a sheetlikeinterposer which is mounted on the integrated circuit device and has aplurality of bonding terminals provided on its periphery and connectedto the plurality of input/output terminals of the integrated circuitdevice respectively. Provided on the sheetlike interposer are aplurality of terminals for external connection which are connected tothe plurality of bonding terminals through wires, respectively. Theinput/output terminals of the integrated circuit device and theplurality of bonding terminals of the sheetlike interposer areinterconnected by respective bonding wires.

The above prior art has such a problem that, since the input/outputterminals of the integrated circuit device and the plurality of bondingterminals of the sheetlike interposer are interconnected by respectivebonding wires, the bonding wires are externally exposed. This leads toanother problem that the bonding tends to be easily separated, resultingin reduced reliability of the package.

In addition, since the bonding wires connecting the plurality ofinput/output terminals of the integrated circuit device and theplurality of bonding terminals of the sheetlike interposer are providedseparately, a long manufacturing time is required.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a mountingassembly of an integrated circuit device which can avoid exposure of aninterconnection between the integrated circuit device and a wiringsubstrate on which the integrated circuit device is to be mounted.

Another object of the present invention is to provide a mountingassembly of an integrated circuit device in which interconnectionsbetween a plurality of input/output terminals of the integrated circuitdevice and a plurality of connecting terminals of a wiring substrate onwhich the integrated circuit device is to be mounted can be carried outsimultaneously.

Yet another object of the present invention is to provide a mountingassembly of an integrated circuit device which can realize a firminterconnection between the integrated circuit device and a wiringsubstrate on which the integrated circuit device is to be mounted.

A further object of the present invention is to provide a mountingassembly of an integrated circuit device in which interconnectionsbetween the integrated circuit device and a wiring substrate, on whichthe integrated circuit device is to be mounted, can be easily, visuallyobserved.

In accordance with an aspect of the present invention, the above objectscan be attained by providing a mounting assembly of an integratedcircuit device which comprises the integrated circuit device havinginput/output terminals on its underside surface, a substrate, on whichthe device is mounted, through-holes formed in a substrate at positionsopposed to the input/output terminals of the integrated circuit device,and a connecting member for connecting the input/output terminals of theintegrated circuit device and the through-holes.

The mounting assembly of the integrated circuit device has electrodesprovided in the through-holes, wires connected to the electrodes, and aplurality of terminals provided on the bottom side of the substrate tobe connected to the wires. The plurality of terminals are arranged in alattice form.

As a connecting member, solder or electrically conductive resin may beemployed.

Further, the substrate may have an external size smaller than or thesame as the integrated circuit device, the connecting member may beexposed externally from the through-holes, and the connecting memberexposed externally from the through-holes may be used as a connectingterminal.

In accordance with another aspect of the present invention, there isprovided a method for manufacturing a mounting assembly of an integratedcircuit device which includes the integrated circuit device having aplurality of input/output terminals provided on its underside and asubstrate, in which, through-holes are provided at positions opposed tothe input/output terminals of the integrated circuit device, said methodcomprising the steps of providing solder for each of the plurality ofinput/output terminals of the integrated circuit device, aligning theplurality of through-holes of the substrate with the plurality ofinput/output terminals of the integrated circuit device, and heating theintegrated circuit device and substrate to melt the solder.

In accordance with a further aspect of the present invention, there isprovided a method for manufacturing a mounting assembly of an integratedcircuit device which includes the integrated circuit device having aplurality of input/output terminals provided on its bottom side and asubstrate, in which through-holes are provided at positions opposed tothe input/output terminals of the integrated circuit device, said methodcomprising the steps of providing a connecting member to each of theplurality of input/output terminals of the integrated circuit device,aligning the plurality of through-holes of the substrate with theplurality of input/output terminals of the integrated circuit device,and simultaneously effecting all the interconnections between theplurality of input/output terminals of the integrated circuit device andthe plurality of through-holes of the substrate.

The above and other objects, features, and advantages of the presentinvention will become apparent from the following description referringto the accompanying drawings which illustrate an example of a preferredembodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a mounting assembly of an integratedcircuit device in accordance with a first embodiment of the presentinvention;

FIG. 2 shows a method for fabricating the mounting assembly of theembodiment; and

FIG. 3 is a cross-sectional view of a mounting assembly of an integratedcircuit device in accordance with the second embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A mounting assembly of an integrated circuit device and a method forproduction thereof in accordance with an embodiment of the presentinvention will be explained in detail with reference to the accompanyingdrawings.

Referring first to FIG. 1, there is shown an embodiment of a mountingassembly of an integrated circuit device in accordance with the presentinvention, which includes an integrated circuit device 1 and a mountingsubstrate 2.

The integrated circuit device 1 is provided on its bottom surface with aplurality of pads 11 for signal input/output or for power input. Thepads 11 are arranged in rows along the periphery of the integratedcircuit device 1. The pads 11 are made of copper or nickel.

The mounting substrate 2 has therein wires 21, a plurality of throughholes 22 and external terminals 23. The outside size of the mountingsubstrate 2 is smaller than or equal to that of the integrated circuitdevice 1. The integrated circuit device 1 is mounted on the uppersurface of the mounting substrate 2.

The mounting substrate 2 comprises a laminate made up of a plurality ofinsulating layers and a plurality of wiring layers. By stacking theseinsulating layers and wiring layers, a desired arrangement of wires 21is formed in the mounting substrate 2. The insulating layers are made ofpreferably material having thermal expansion coefficient of the same asor similar to that of the integrated circuit device 1. Morespecifically, the material of the insulating layers is ceramic, whilethe material of the wiring layers is copper.

The through holes 22 each are disposed so as to be opposed to respectivepads 11 provided on the integrated circuit device 1. The through holes22 are formed so as to have a diameter of the same as or similar to thatof the pads 11 of the integrated circuit device 1. More specifically thethrough holes 22 each have a diameter of 0.2 mm. A metallized electrode24 is formed over the side surface of each of the through holes 22. Thethrough holes 22 each are filled with solder 25.

The electrodes 24 are connected to the wires 21 in the mountingsubstrate 2. Each of the electrodes 24, which is formed by plating theinside wall of the through holes 22 with copper, has a thickness of 1micron.

The external terminals 23 are arranged, on a lattice pattern, on thelower surface of the mounting substrate 2. The external terminals 23 areelectrically connected respectively to the pads 11 of the integratedcircuit device 1 through the wires 21, electrodes 24 and through-holes22, respectively. That is, signals inputted from the external terminals23 are transmitted to the integrated circuit device 1 through the wires21, electrodes 24, solders 25 and pads 11 of the integrated circuitdevice 1.

The solder 25 interconnects electrically and mechanically the electrodes24 provided on the inside surface of the through hole 22 and the pad 11of the integrated circuit device 1. The solder 25 is filled into thethrough holes 22 to such an extent that the solder can be visuallychecked from the lower side of the mounting substrate 2. Morepreferably, the solder is filled so as to be exposed from the lowersurface of the mounting substrate 2, and the solder 25 is made of Sn/Pballoy.

Thus, in accordance with the present embodiment, the mounting substrate2 to be mounted with the integrated circuit device 1 is provided withthe through holes 22 at positions opposed to the pads 11 of theintegrated circuit device 1 to connect the pads 11 to the through holes22. Thus, the interconnection between the integrated circuit device 1and the mounting substrate 2 is not exposed to the outside, with theresult that the reliability of the connection can be improved.

Further, the solder 25 filled into the through holes 22 can be observedfrom the lower side of the mounting substrate 2, and therefore theconnection between the pads 11 of the integrated circuit device 1 andthe through holes 22 of the mounting substrate 2 can be checked.

A detailed explanation will next be made as to the method forfabricating the mounting assembly of the integrated circuit device ofthe present invention, by referring the drawings. The fabricating methodof the present invention is featured by a step of simultaneouslyinterconnecting a plurality of pads 11 of the integrated circuit device1 and through-holes 22 of the mounting substrate 2 by means of aconnecting member.

Referring to a first step of FIG. 2(a), solder 25 is provided for eachof the pads 11 provided on the lower surface of the integrated circuitdevice 1. The solder 25 is preferably comprised of a solder ball. Theamount of each solder 25 is such that each through hole 22 of themounting substrate 2 can be sufficiently filled with the solder.

Referring next to a second step of FIG. 2(b), an alignment between theintegrated circuit device 1 and the mounting substrate 2 is carried out.More in detail, the integrated circuit device 1 is positioned on themounting substrate 2 so that the pads 11 on the lower side of theintegrated circuit device 1 are opposed to the through holes 22 providedin the mounting substrate 2.

Referring to a third step of FIG. 2(c), both the integrated circuitdevice 1 and mounting substrate 2 are heated to melt the solders 25. Thesolders 25 are melted and filled into the through holes 22, so that theintegrated circuit device 1 is electrically and mechanically connectedto the mounting substrate 2.

In accordance with the method for producing the mounting assembly of theintegrated circuit device of the foregoing embodiment, since the solders25 is melted to connect the integrated circuit device 1 to the mountingsubstrate 2 by heating the whole of the mounting substrate 2 havingthere on the integrated circuit device 1, simultaneous connection can berealized between the pads 11 of the integrated circuit device 1 and thethrough holes 22.

Explanation will now be made in detail as to a second embodiment of thepresent invention, by referring to FIG. 3. The second embodiment of thepresent invention is featured in that the pads 11 provided on the lowerside of the integrated circuit device 1 are electrically andmechanically connected to the through holes 22 of the mounting substrate2 using electrically conductive resin. In other respects, the secondembodiment is substantially the same as that of the first embodiment.

Referring to FIG. 3, a conductive resin 3 is filled into each of throughholes 22. The conductive resin 3 electrically connects the pad 11 of theintegrated circuit device 1 and an electrode 24 provided on the insidewall of the through holes 22. The conductive resin 3 is, for example, anepoxy resin. Employment of the conductive resin 3 restrains amounts ofheat applied to the integrated circuit device 1 and mounting substrate 2as compared with solder.

A method for producing the mounting assembly of the integrated circuitdevice in accordance with the second embodiment of the present inventionwill next be explained with reference to FIG. 3.

The electrically conductive resin 3 is applied beforehand onto the pads11 of the integrated circuit device 1. The conductive resin 3 is filledinto the through holes 22 of the mounting substrate 2 beforehand. Next,the integrated circuit device 1 and mounting substrate 2 are oppositelypositioned so that the pads 11 of the mounting substrate 2 are alignedwith through holes 22 filled with the conductive resin 3 respectively.In the case that the conductive resin 3 is such thermosetting resin asepoxy resin, when heated, the pads 11 are connected simultaneously tothe through holes 22, respectively.

Consequently, since the interconnection between the integrated circuitdevice 1 and mounting substrate 2 can be realized at low temperature inthe present embodiment, any warpage of the mounting substrate 2 can berestrained, connection reliability can be improved and the amount ofheat necessary to be applied to the integrated circuit device 1 can bereduced.

Although a plurality of insulating layers and a plurality of wiringlayers are stacked on the mounting substrate 2 in the foregoingembodiments, the substrate may be made up of a single insulating layerand a single wiring layer provided thereon. In that case, a desiredwiring is formed by the use of a single wiring layer. With such anassembly, since the thickness of the mounting substrate 2 in thestacking direction thereof can be reduced, the mounting height of theintegrated circuit device can be advantageously reduced.

Though the insulating layers of the mounting substrate 2 are made ofceramic in the foregoing embodiments, the material of the insulatinglayers is not limited to the above example and the insulating layer maycomprise such a flexible material as a polyimide film.

In the foregoing embodiments, further, a solder 25 exposed from thelower side of the mounting substrate 2 may be used as an electrode.Signals inputted from the electrodes 25 comprising exposed solder aretransmitted to the pads 11 of the integrated circuit device 1 throughthe filled solder of the through holes 22. Such electrodes can be usedmore preferably as grounding electrodes, since the grounding electrodeshave a width larger than that of the other wiring 21.

In the mounting assembly of the integrated circuit device of the presentinvention, it will be appreciated from the foregoing explanation thatthe mounting assembly having the integrated circuit device mountedthereon is provided with the through-holes at such positions as to beopposed to the input/output terminals provided on the lower side of theintegrated circuit device to connect the input/output terminals of theintegrated circuit device with the through-holes, whereby theinterconnection between the integrated circuit device and mountingsubstrate can be prevented from being outwardly exposed, therebyimproving the interconnection reliability.

Further, the connection between the input/output terminals of theintegrated circuit device and the through-holes of the mountingsubstrate can be checked by observing the solder or conductive resinfilled in the through-holes from the lower side of the mountingsubstrate.

In accordance with the method for producing the mounting assembly of theintegrated circuit device of the present invention, since the integratedcircuit device can be connected to the mounting substrate by heating thewhole of the mounting substrate having the integrated circuit devicemounted thereon to melt the solder or to thermally set the resin, theconnections between input/output terminals of the integrated circuitdevice and through holes can be simultaneously effected.

It is to be understood that variations and modifications of embodimentsof the invention disclosed herein will be evident to those skilled inthe art. It is intended that all such modifications and variations beincluded within the scope of the appended claims.

What is claimed is:
 1. A method for manufacturing a mounting assembly ofan integrated circuit device, said mounting assembly including (1) anintegrated circuit device having a surface on which a plurality ofinput/output terminals are provided, and (2) a substrate, said methodcomprising the steps of: providing solder on each of said input/outputterminals of said integrated circuit device, forming through-holes insaid substrate at positions corresponding to said input/output terminalsof said integrated circuit device, each of said through-holes havingsubstantially the same diameter as a corresponding input/output terminalof said integrated circuit device, positioning said through-holes ofsaid substrate respectively in opposition to said input/output terminalsof said integrated circuit device, and heating said integrated circuitdevice and said substrate to melt said solder.
 2. A method formanufacturing a mounting assembly of an integrated circuit device, saidmounting assembly including (1) an integrated circuit device having asurface on which a plurality of input/output terminals are provided, and(2) a substrate, said method comprising the steps of: providingconnecting members respectively on said input/output terminals of saidintegrated circuit device, forming through-holes in said substrate atpositions corresponding to said input/output terminals of saidintegrated circuit device, each of said through-holes havingsubstantially the same diameter as a corresponding input/output terminalof said integrated circuit device, positioning said through-holes ofsaid substrate respectively in opposition to said input/output terminalsof said integrated circuit device, and simultaneously connecting saidinput/output terminals of said integrated circuit device with saidthrough-holes of said substrate via said connecting members.